I haven't used it on myself, but I'm a veterinarian so can speak about it a bit. Lufenuron inhibits the formation of chitin, which is present in the cell wall of fungi, thus inhibiting the ability to reproduce. It was initially developed as a flea preventative (chitin is also present in flea eggs and exoskeletons of adults), but has since been used with success to treat ringworm (skin fungus) infections in animals also. It's extremely safe in dogs and cats - they can eat the whole box without mishap.

Of course, I'm not a physician and can't speak to its safety in humans. Sorry if that's not terribly helpful.